Add a 2nd radiator in custom loop?

George Hudson · 8 Jan 2020 at 08:00

I am running a custom loop consisting of the EK kit P360. https://www.ekwb.com/shop/ek-kit-p360 which has a single 360x38mm radiator. I have a Ryzen 3900X and EVGA RTX 2080 Ti in the loop in the sequence of pump/reservoir to GPU to CPU then to radiator and back to pump/resevoir. After an hour of overclocked GPU stress testing I am seeing GPU temps of 48-51c and CPU temps of 45-50c so both around the same. I am thinking of adding a second radiator (the same as that which is fitted) between the GPU and CPU. Will this be a waste of money? What kind of temperature drops can I expect to see? Thanks.

George Hudson · 8 Jan 2020 at 08:21

I appreciate the quick response. I think I got it in my head after watching quite a few Youtube guides that I needed radiators that provided a surface area for 4x120mm fans for my setup. One fan for each component in the loop and an additional fan for each component if overclocking, so admittedly based on that another 360 radiator would be overkill (unless I bought another GPU

but spent enough on PC for a while). Noise wise the system is nice and quiet and that is the principal reason i went for this setup. I will leave the system as is and monitor temps as I play games. Thanks again.

George Hudson · 9 Jan 2020 at 05:55

I did more 3DMark benchmarking last night and I am consistently seeing 47-48 deg C on both CPU and GPU and hitting results above 98% of other benchmarks on 3DMark website. My inlet temps are 26 deg C and inside case is generally 5-6 deg C above. I was running a GPU overclock of +800 on memory and +130 on GPU Clock. Spec as follows :- Cooler Master H500M case, Gigabyte X570 Aorus Master Motherboard, AMD Ryzen 9 3900X, G.Skill Trident Z RGB 32GB DDR4-3600 Memory, Samsung 970 Evo Plus 500 GB NVME SSD, Samsung 860 Evo 500GB SSD, EVGA XC Ultra GeForce RTX 2080 TI in EK Waterblock, EVGA SuperNOVA P2 850W PSU, EK-KIT P360 Water Cooling loop, 4 x Cooler Master MF120R ARGB 59CFM fans, LG 34GK950F-B monitor

George Hudson · 18 Jan 2020 at 19:59

Can you recommend suitable in-line water temp sensors? I have two temp sensor headers on mobo which I currently use for ambient and case internal air temps but would use those headers for water temps instead. Probably monitor pre and post radiator water temps.

George Hudson · 4 Mar 2020 at 17:21

I fitted the temperature sensor recommended by LuckyBenski a couple of weeks ago. No problems with fitting it immediately on the exit of the radiator. Readings appear to be fine. I have been logging a lot of data while playing around with the fan curves and playing games/running Heaven benchmark. I am using the temperature sensor as the controlling sensor for the radiator fans speed. The most I have seen the ambient/water Delta-T at is 13 degrees C but I have now got it to a pretty constant 10 degrees C. My curiosity has got the better of me and I have just ordered a 2nd 360mm radiator although it is thinner than my front mounted one being only 28mm thick due to the amount of room at the top of the case. I have also ordered a BarrowCH OLED display flow meter which can be hooked up to a fan header for monitoring. I am not expecting to get Delta-T any lower. What I am hoping to achieve is lowering the fan speeds even though the system is pretty quiet as it is. At present I am running pump at 30% constant, inlet fans on radiator between 40% and 50% depending on Delta-T and the 4 exhaust fans at 40% constant. The two constant fan speed values are while I have been determining optimal radiator fan settings. I will post this thread with my test results regarding 2nd radiator.

George Hudson · 7 Mar 2020 at 20:49

Just got my system back together with second radiator in and flow meter. I was shocked to learn that running my water pump at 30% was circulating less than 0.3 litres per min. Quick test to establish all flow rates from 100% down to 40% gave a range of 6.8 to 1.3 liters, so I have settled for now running 50% which equates to 2.55 litres min and its maintaining a Delta-T of 9 degrees C. Lots of testing to do. Keep you posted.

George Hudson · 17 Mar 2020 at 23:19

Update.

I am using the Cooler Master H500M case with a EK-XRES 140 Revo D5 PWM combo pump and reservoir. Also fitted is a Aqua Computer water temperature sensor and Barrow flow meter. An ambient temperature sensor is connected to the motherboard and located just to the side of the front 2x200mm fans.

I am running a 360mm radiator at 38mm thick positioned at the front of the case, with 3x120mm Vardar fans inside the case pulling the air through the radiator and 2x200mm fans in front of the radiator pushing air through it. Possibly not the best configuration. I may try removing the 2x200mm fans in case they are reducing the air flow through the radiator.

In the top of the case I have a 360mm radiator at 28mm thick with 3x120mm Cooler Master MasterFan SF120R ARGB in push configuration, expelling air from inside the case through the radiator. I also have 1 of these fans on the rear of the case pushing internal case air out. So 9 fans in total.

The custom loop is setup from reservoir and pump -> flow meter -> GPU -> top radiator -> CPU -> front radiator -> temperature sensor -> back to reservoir and pump.

I am running my EVGA RTX 2080 Ti with a stable overclock of +800 on memory and +125 on the GPU seeing 2070Mhz in the EVGA Precision X1 software.

I have data logged over 30 hours of testing.

The best Delta-T I achieved was during a 200 minute run of Heaven benchmark with the pump and all fans at 60%. The 2x200mm fans always run at full speed. This produced an average Delta-T of 6 degrees C with ambient at 26 and coolant at 32 degC. The fans were audible but in no way loud. The mobo temp sensor averaged 39 degC with the CPU average at 42 degC ( and a peak of 51), the GPU average at 37 degC (with a peak of 48).

The fan and pump speeds I am currently using, after a total of 390 minutes of testing with Heaven benchmark are 40% pump (moving 1.27 litres/min), 50% front fans, 40% top and rear fans. Over 4 runs, this produced a repeatable average Delta-T of 8 degrees C over ambient. The fans are quiet. The mobo temp sensor averaged around 40 degC with the CPU around 46 degC ( and a peak of 77), the GPU 45 degC (with a peak of 52).

I used HWinfo64 to record these sensors.

My pump has developed a fault in that the sense signal to the mobo header is not producing a signal. I can still control the speed of the pump on the PWM speed control line but not getting the RPM data from the pump. I have contacted EK and their customer support is brilliant. Communication has been very rapid over 24 hours since reporting the problem via emails. A replacement pump is on its way and collection of faulty unit at a time suitable for me when I have swapped them over. I have no regrets in purchasing the EK kit and very happy with the results I am achieving.

George Hudson · 18 Mar 2020 at 22:42

The noisiest fans in my system are the 2x200mm sitting in front of the front radiator. These are connected directly to the 12v and speed can not be adjusted. I am going to remove them and see what effect it has on temps. I like the argb lighting on them so may replace them with a set of the speed controllable 3x120mm I have in the top. Fun times.

George Hudson · 19 Mar 2020 at 13:24

I have removed the 2x200mm front fans. I was correct in that a lot of the noise was produced by them. Came across this interesting read regarding fan configuration and speeds. https://www.ekwb.com/blog/push-pull-or-push-pull-on-radiators/

I left the fan and pump speeds as before to make a comparison test of with and without the 2x200mm front fans. After a total of 158 minutes of testing with Heaven benchmark there was a Delta-T of 11 degrees C over ambient. The mobo temp sensor averaged 42 degC with the CPU average of 49 degC ( and a peak of 57), the GPU average of 47 degC (with a peak of 52).

In conclusion, those 2x200mm fans each producing 90 CFM and 28 dBA do make a difference of 3 degC to the Delta-T and keep the CPU, GPU and mobo components running a few degrees cooler. Obviously more testing would be required.

Any how, I have taken this thread off topic.

Thank you to all those who gave advice. I did fit a second radiator along with a flow meter and a water temperature sensor. Collectively, these parts have helped me to data log my system in order to produce an optimal ramping curve for the fans and pump while gaining a better understanding of a water cooled system.